Electrodeposition of nickel



3,506,548 ELECTRODEPOSITION OF NICKEL Joseph R. Duchene, Southfield, Mich., assignor to Allied Research Products, Incorporated, Baltimore, Md., a corporation of Maryland No Drawing. Filed Sept. 23, 1966, Ser. No. 581,461 Int. Cl. C23b /46, 5/08; C22d 1/14 U.S. Cl. 20449 5 Claims ABSTRACT OF THE DISCLOSURE This invention relates to the electrodeposition of nickel and more particularly to electroplating solutions adapted to produce bright nickel deposits. The bright nickel deposits produced according to this invention exhibit improved ductility and throwing or covering characteristics and thus are capable of improved coverage of imperfections in the base metal.

It has now been found that improved bright and/or semi-bright nickel deposits can be obtained using a conventional aqueous acidic nickel plating bath provided with saturated aliphatic sulfonic acid having the structural formula R -(CH -SO R wherein R is a substituent selected from the group consisting of hydroxy, and hydroxy lower alkyl, and R is a cation whose presence in the bath is not deleterious and includes the alkali metals and the alkaline earth metals. R is preferably hydrogen, ammonium, sodium, potassium, magnesium or even nickel.

Representative suitable brightening agents of this invention include 2-hydroxy ethane sulfonic acid, hydroxy propane sulfonic acid, hydroxy butane sulfonic acid, the alkali and alkaline earth metal salts and mixtures thereof.

It has been found particularly advantageous to employ the sodium or potassium salt of the above aliphatic saturated sulfonic acids thereby increasing the water solubility of the brightening agent.

The novel brightener of this invention is generally used in amounts between 0.01 to 300 grams/ liter of bath solution and preferably between 1 to 3 grams/liter of solution.

In general, the process of this invention involves operating a bath at conventional nickel plating temperatures ranging from about room to boiling though usually most convenient temperatures of operation are from about 120 F. to 170 F. The best pH values for the bath range from about 2.5 to 5.0 though a pH as low as 2 and as high as 6 can also be employed. Preferably, the pH will range between 3.0 and 5.0 in the majority of the cases. The cathodic current densities to be used average generally from about 10 to 200 amp/ sq. ft. depending, for instance, on the temperature, degree of solution agitation and the composition of the bath. Higher temperatures and more rapid agitation permit higher current densities to be used effectively.

Baths for electroplating in accordance with this invention contain at least one nickel salt as a source of nickel and include well known Watts-type bath and high chloride type bath. The Watts bath solution typically comprises around 200-400 grams/ liter of nickel sulfate, 30-75 grams/liter of nickel chloride and 30-50 grams/liter of boric acid. A high chloride type bath can contain about 150-300 grams/liter of nickel chloride, 40-150 grams/ liter of nickel sulfate and 30-50 grams/liter of boric acid.

United States Patent 0 3,506,548 Patented Apr. 14, 1970 Considerable latitude is also permissible in respect to the types and concentrations of the nickel salts employed. For instance, as the source of nickel, nickel sulfamate as well as a combination of nickel fluoborate with nickel sulfate and nickel chloride or a combination of nickel fluoborate with nickel chloride can be employed.

Additionally, the bath can include additional brighteners, for instance an aromatic sulfur compound such as saccharin, p-toluene sulfonamide, o benzoyl sulfimide, benzene sulfonamide, naphthalene sulfonic acid, benzene sulfonic acid, 2-butyne, 1,4-disulfonic acid, allyl sulfonic acid, together with 2-butyne, 1,4-dioxyethane sulfonic acid. Generally, the aromatic sulfur compound will be present in amounts ranging from 0.1 to 10 grams/liter of solution.

Additionally water-soluble acetylenic compounds can also be effectively included in the bath solution of this invention. Particularly effective acetylenic compounds include 2-butyne-l,4-diol, 4-methoxy-2-butyn-l-ol, 3-hexyne- 2,5-diol, 4-diethylamino-2-butyn-l-ol, 4-(N-morpholinyl)- 2-butyn-1-ol, 3-pentyn-l-ol, 2,4-hexadiyne-1,6-diol and 1-diethylamino-2-propyne. Conveniently the water soluble acetylenic compound can be employed in amounts ranging from 0.01 to 0.3 grams/liter of solution.

For the purpose of giving those skilled in the art a better understanding of the invention, illustrative examples are given. In the examples, an aqueous acidic nickelcontaining bath was made up with specified components. Electrodeposition was carried out by passing electric current through an electric circuit comprising an anode and a sheet metal or rod cathode, both immersed in the bath. The baths were agitated, usually by moving the cathode although incertain instances air agitation or other mechanical or electrical agitation means can be employed.

In the following examples, the below described standard Watts-type bath was used as a base solution:

Nickel sulfate g./ 1-- 300 Nickel chloride g./l 60 Boric acid g./l 40 pH 3.0-5.0 Temperature C 40-65 Current density amperes/dm. 1-20 EXAMPLE 1 G./l. 2-hydroxy ethane sulfonic acid, sodium salt 4 Sodium saccharin 3 2-butyne 1,4-diol 0.2

EXAMPLE 2 6/1. 2-hydroxy ethane sulfonic acid, sodium salt 12 Sodium saccharin 3 2-butyne 1,4-diol 0.2

EXAMPLE 3 G./l. 2-hydroxy ethane sulfonic acid 2 EXAMPLE 4 6/1. 3-hydroxy propane sulfonic acid, sodium salt 2 Z-butyne 1,4-diol 0.1

EXAMPLE 5 G./l. 4-hydroxy butane sulfonic acid 4 Sodium saccharin 1 Unless otherwise specified all parts and percentages in the specification and claims are by weight. The foregoing examples illustrate specific baths and processes, several being preferred. It is to be understood that the compositions and conditions can be varied, for instance, in the use of a high chloride type bath or a nickel sulfamate bath. Therefore, as manyrembodiments of this invention may be made without departing from the spirit and scope thereof, the invention includes all such modifications and variations as come within the scope of the appended claims.

What is claimed is:

1. An aqueous acidic electroplating bath solution for producing bright deposits of nickel comprising at least one nickel salt as a source of nickel and, as a brightener, a saturated aliphatic sulfonic acid in amounts sutficient to produce a bright nickel deposit, said sulfonic acid having the structural formula R (CH SO -R wherein R is a substituent selected from the group consisting of hydroxy and hydroxy lower alkyl and R is a cation selected from the group consisting of hydrogen, ammonium, alkali metal and alkaline earth metal.

2. The bath solution of claim 1 wherein the sulfonic acid is present in amounts of 0.01 to 300 g./l.

3. The bath solution of claim 1 wherein said sulfonic acid is Z-hydroxy ethane sulfonic acid.

4. The bath solution of claim 1 including saccharin 4 in amounts ranging from 0.1 to 10 g./l. of solution and Z-butyne- 1-4 -diol in amounts ranging from 0.01 to 0.3 g./l.

5. The bath solution of claim 1 wherein the saturated aliphatic sulfonic acid is selected from the group consisting of 2-hydroxy ethane sulfonic acid, hydroxy propane sulfonic acid, hydroxy butane sulfonic acid, the alkali metal and alkaline earth metal salts thereof and their mixtures.

References Cited UNITED STATES PATENTS 2,712,522 7/1955 Kardos et al. 20449 2,800,442 7/1957 Brown 204-49 2,910,413 10/1959 Strauss et al. 20449 X 2,937,978 5/1960 Strauss et al. 20449 PATRICK P. GARVIN, Primary Examiner W. H. CANNON, Assistant Examiner US. Cl. X.R. 204-112 

